Re: Prius owner please test this, was RE: Prius comments

[Lee Hart <leeahart@earthlink.net>]

Chris Meier wrote:
> I was wondering if a Prius owner would conduct a test.
> If your foot isn't on the brake, and the transmission is
> still in 'D', will the motor restart to satisfy the air conditioning
> need, and if so, will the car move forward?

We bought my wife a Prius, and just got it about 2 weeks ago.

The Prius' behavior is independent of whether the ICE is running or not.
If you're shifted into Drive, the car creeps ahead like any ICE with an
automatic transmission, regardless of whether the ICE is running or not.

I'll try to explain the ICE's behavior for those who may be
contemplating a hybrid.

 - When you turn the key to "start" momentarily, it latches a 'Ready'
   light "on". The ICE typically starts a within a second by itself.
   You are not controlling cranking; the system does it automatically.

 - The ICE will run to top off the battery, support the air conditioning
   (which may initially be running at max cool), etc. If you don't
   actually begin driving, the ICE shuts off in a minute or so.

 - You put it in R (Reverse), D (Drive), or B (Braking, or "low" gear,
   for more engine braking). The car creeps without touching the
   accellerator pedal, just like any car with an automatic transmission.

 - As long as you don't press the accellerator too much, and the battery
   is more than half charged, the car runs as a pure electric.

 - You can drive up to 42 mph as pure electric. Accelleration is VERY
   slow. It feels like the electric motor is only good for a few HP, so
   on level ground you won't even reach 42 mph (more like 30-35 mph).

 - The ICE will start a) when the battery reaches about 1/2 charge,
   b) you go faster than 42 mph, c) you step down on the accellerator
   a little harder.

 - Once started, the ICE runs until a) the battery is recharged, or
   b) you let up the accellerator enough so it can switch back to
   electric.

The full algorithm is certainly more complicated. In general, it seems
to be looking for cases where the power required by the ICE is too low
to bother to run it. For example, it will shut off the ICE if you're
going down a long hill on the freeway and use the electric motor to
maintain speed, even though you're still going over 60 mph. And there
are certain speeds, around 45-50 mph, where it will cycle the ICE on and
off even though there was no change in speed or accellerator pedal
position.

Basically, you have to get used to ignoring the ICE. It starts and stops
as it pleases, without the car's behaviour changing! Luckily, the ICE is
so quiet that it is hard to tell when it is running anyway!

So far, we averaged 50 mpg and got 540 miles on our first tank of gas.
It only gets 42 mpg at 70-75 mph on the expressway, but driving around
town at low speeds, it easily tops 60 mpg.
-- 
Lee A. Hart                Ring the bells that still can ring
814 8th Ave. N.            Forget your perfect offering
Sartell, MN 56377 USA      There is a crack in everything
leeahart_at_earthlink.net  That's how the light gets in - Leonard Cohen